This method and apparatus are intended, in particular, to complement the analysis methods and apparatuses described in French patent applications Nos. 8416448 filed Oct. 26, 1984, 8419719 filed Dec. 21, 1984, 8504476 filed Mar. 26, 1985, 8504477 filed Mar. 26, 1985, etc.
When examining blood, blood is taken from a patient by means of a tube including an anticoagulant, and is then centrifuged in order to collect red corpuscles at the end of the tube, with analyses being performed on the plasma located above the corpuscles. Modern analysis techniques require only a very small quantity of plasma, and preferred implementations of the invention provide a method and apparatus enabling very small quantities of plasma to be transferred to the above mentioned analysis apparatuses from a very small initial quantity of blood, thus providing a considerable improvement for the patient.
Preferred implementations of the present invention provide a method of delivering a predetermined quantity of plasma from a blood sample having a volume of a few microliters.
A difficult problem arises when transferring such very small samples of liquid because of the capillary nature of the ducts interconnecting the receptacle to the various cells.
The use of centrifugal force which has the apparent effect of increasing the density of the liquid used serves to overcome the problems of capillary retention.